As global warming and environmental pollution have emerged as serious problems, research and development of environmentally-friendly cars capable of minimizing environmental pollution are actively conducted and markets therefor are gradually extended. As environmentally-friendly cars, electric vehicles, hybrid vehicles and plug-in vehicles which employ motors generating driving power using electric energy, instead of engines generating driving power by burning fossil fuel, are on the market worldwide.
Most environmentally-friendly vehicle technologies using electric energy generate vehicle driving power by providing electric energy stored in a high-voltage battery of a vehicle to an electric motor.
Such motor driving control used in environmentally-friendly vehicles requires an inverter for converting DC power provided by a battery into multi-phase AC power necessary for motor driving. Although a method of providing multi-phase AC power to a motor using a single inverter has been used, research on a dual inverter method for providing power to a motor using two inverters is underway.
An inverter converts a DC voltage applied from a battery to generate an AC voltage by on/off controlling switching elements through pulse width modulation and provides the generated AC voltage to a motor to drive the motor. When the AC voltage is supplied from the inverter to the motor, current consumed by the motor can be reduced under the same power conditions if the AC voltage is provided to the motor through 6 steps. 6-step voltage supply to the motor can improve system efficiency and fuel efficiency of environmentally-friendly vehicles such as electric cars/hybrid cars/fuel cell cars equipped with the motor as well as increasing power and efficiency of the inverter and the motor.
Accordingly, the relevant technical field requires a dual inverter control method capable of improving power efficiency of an inverter and a motor by controlling a dual inverter through 6-step control to apply a voltage to the motor in a motor driving system using the dual inverter.
The matters disclosed in this section are merely for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that the matters form the related art already known to a person skilled in the art.